^^^ AND ^^^^ 



JOURNAL OF VARIATION. 



Vol. IX. No. 12. December Ioth, 1897. 



Notes on hybrid Smerinthus popuIi=ocellatus. 



By A. BACOT. 



After many trials, in different seasons, I was at last, in June, 

 1896, fortunate in obtaining two pairings between Siuerinthus populi 

 and S. ocellatus. 



Ovum. — Early in June I found, in one of my cages, a male Sme- 

 rinthm poindt, hi copula with a female S. ocellatus. One hundred and 

 seventy-eight eggs were laid by the 5 , and, although some slight 

 colour changes took place, none of them hatched. Many turned dark 

 before shrivelling up, and, since infertile eggs of Smerinth'KJi do not 

 change colour, but remain green even after drying up, whilst fertile 

 eggs become whitish before hatching, it is very probable that a cer- 

 tain amount of development took place within the eggs. 



On June 13th, a male <S. ocellatus paired with a female S. populi. 

 As I was leaving London for a week on the 19th, I handed the eggs 

 over to my friend Mr. J. A. Simes, who kindly took charge of them 

 during my absence. He informs me that they commenced to hatch 

 on the 24th, and, upon my return on the 27th, there were twenty- 

 eight living larvae and a number of dead ones ; a few more hatched 

 after this date, but they were very weakly, and soon followed the 

 majority. A careful examination of the ova, on July 3rd, showed that 

 of 163 eggs laid, 59 had hatched, in 55 the young larvte appeared to 

 have fully developed, but from some unexplained cause had not 

 emerged ; 27 were still green (these afterwards dried up), and of the 

 remainder some were very discoloured (having probably died during 

 the development of the embryo), and others had shrivelled up without 

 change (probably unfertilised). 



Larva. — June 29th, l.s^ skin : length between one-eighth and three- 

 sixteenths of an inch when newly hatched, growing to between three- 

 eighths and seven-sixteenths before the first moult. Hea<l : green, large, 

 rounded, but with a tendency to triangular shape ; a few scattered hairs 

 and a yellow inverted V on face. Body : pale green ; scutellum fairly 

 distinct ; a faint dark, medio-dorsal line ; two tubercles on the dorsal 

 area of the thoracic segments can be distinguished as rather larger, 

 and bearing longer hairs than the usual shagreen tubercles. The 

 trapezoidals on abdominal segments can also be observed standing 

 out among the shagreen tubercles, though not quite so clearly as the 

 two above-mentioned on the thoracic segments. (This last feature 

 is not distinctive of the hybrid larvag ; it can also be seen in the larva 

 of »S', ocellatus., and is probably present in that of N. popidi and -S'. tiliae. 



